How to find CUDNN with CMake?

Question

Apparently I correctly installed CUDA and CUDNN, but still FindCUDA finds CUDA, but FindCUDNN.cmake does not find CUDNN

What else should I check to debug this?

OS: Windows 10

cmake version 3.17.2

CUDA Version 10.2

CUDNN version cudnn-10.2-windows10-x64-v7.6.5.32

CUDA installed with installer, to C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v10.2

PATH set as instructed

CUDNN files copied into respective bin, include, and lib folders

[cmake] -- Found CUDA: C:/Program Files/NVIDIA GPU Computing Toolkit/CUDA/v10.2 (found version "10.2") 
[cmake] CMake Error at C:/Program Files/CMake/share/cmake-3.17/Modules/FindPackageHandleStandardArgs.cmake:164 (message):
[cmake]   Could NOT find CUDNN (missing: CUDNN_LIBRARY CUDNN_INCLUDE_DIR)
[cmake] Call Stack (most recent call first):
[cmake]   C:/Program Files/CMake/share/cmake-3.17/Modules/FindPackageHandleStandardArgs.cmake:445 (_FPHSA_FAILURE_MESSAGE)
[cmake]   cmake/FindCUDNN.cmake:90 (find_package_handle_standard_args)
[cmake]   CMakeLists.txt:17 (find_package)

The FindCUDNN.cmake: https://gist.github.com/WurmD/26af2940d8dec7cc48d38bc30fd1b3ef

Answer 1

...
set "cudaRoot=C:/Program Files/NVIDIA GPU Computing Toolkit/CUDA/v11.3"
...
-DCUDNN_LIBRARY="%cudaRoot%\lib" ^
-DCUDNN_INCLUDE_DIR="%cudaRoot%\include" ^
...

Answer 2

I was compiling OpenCV with Visual Studio 2019; so I'll just go ahead and assume you were too - since I'm tired and I just got this issue resolved for myself.

0. Be sure to REBOOT/RESTART your PC after "installation" of CUDNN
1. Do a fresh GIT clone of opencv as well as opencv_contrib
2. Be sure to make the BUILD folder in the opencv directory
3. Set your required environmental variables; something like this but fill in your paths:

---

    set "CUDA_PATH=............/NVIDIA GPU Computing Toolkit/CUDA/v11.0"
    set "opencvSource=opencv"
    set "opencvExtraModules=opencv_contrib\modules"
    set "opencvBuild=%opencvSource%\build"
    set "compiler=Visual Studio 16 2019"
    set "buildType=Release"
    set "python3_executable=............/AppData/Local/Programs/Python/Python38/python.exe"
    set "python3_include_dir=............/AppData/Local/Programs/Python/Python38/include"
    set "python3_library=............/AppData/Local/Programs/Python/Python38/libs/python38.lib"
    set "python3_numpy_include_dirs=............/AppData/Local/Programs/Python/Python38/Lib/site-packages/numpy/core/include"
    set "python3_packages_path=............/AppData/Local/Programs/Python/Python38/Lib/site-packages"

---

4. Re-run CMAKE (obviously change this to match your options), mine were:

---

    cmake ^
    -B"%opencvBuild%/" ^
    -H"%opencvSource%/" ^
    -G"%compiler%" ^
    -Ax64 ^
    -DCMAKE_BUILD_TYPE=%buildType% ^
    -DBUILD_opencv_python3=ON ^
    -DBUILD_opencv_world=ON ^
    -DBUILD_EXAMPLES=OFF ^
    -DBUILD_opencv_python_bindings_generator=ON ^
    -DOPENCV_PYTHON3_VERSION=3.8.3 ^
    -DPYTHON3_EXECUTABLE="%python3_executable%" ^
    -DPYTHON3_INCLUDE_DIR="%python3_include_dir%" ^
    -DPYTHON3_LIBRARY="%python3_library%" ^
    -DPYTHON3_NUMPY_INCLUDE_DIRS="%python3_numpy_include_dirs%" ^
    -DPYTHON3_PACKAGES_PATH="%python3_packages_path%" ^
    -DINSTALL_TESTS=OFF ^
    -DINSTALL_C_EXAMPLES=OFF ^
    -DOPENCV_EXTRA_MODULES_PATH="%opencvExtraModules%/" ^
    -DWITH_CUDA=ON ^
    -DCUDA_ARCH_BIN=6.1^
    -DCUDA_ARCH_PTX=7.5^
    -DCUDA_FAST_MATH=ON ^
    -DBUILD_PROTOBUF=ON